CN109206155B - A kind of method for preparing slow-release urea - Google Patents
A kind of method for preparing slow-release urea Download PDFInfo
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- CN109206155B CN109206155B CN201811248231.9A CN201811248231A CN109206155B CN 109206155 B CN109206155 B CN 109206155B CN 201811248231 A CN201811248231 A CN 201811248231A CN 109206155 B CN109206155 B CN 109206155B
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- diisocyanate
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- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 73
- 239000004202 carbamide Substances 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000006243 chemical reaction Methods 0.000 claims abstract description 43
- 239000003054 catalyst Substances 0.000 claims abstract description 24
- 239000002245 particle Substances 0.000 claims abstract description 21
- 239000004814 polyurethane Substances 0.000 claims abstract description 16
- 229920005989 resin Polymers 0.000 claims abstract description 14
- 239000011347 resin Substances 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 13
- 239000007787 solid Substances 0.000 claims abstract description 10
- 229920002635 polyurethane Polymers 0.000 claims abstract description 8
- 150000001875 compounds Chemical class 0.000 claims abstract description 7
- 125000005442 diisocyanate group Chemical group 0.000 claims abstract description 7
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 21
- ARXKVVRQIIOZGF-UHFFFAOYSA-N 1,2,4-butanetriol Chemical compound OCCC(O)CO ARXKVVRQIIOZGF-UHFFFAOYSA-N 0.000 claims description 14
- XFNJVJPLKCPIBV-UHFFFAOYSA-N trimethylenediamine Chemical compound NCCCN XFNJVJPLKCPIBV-UHFFFAOYSA-N 0.000 claims description 12
- 150000005676 cyclic carbonates Chemical class 0.000 claims description 9
- 229920000768 polyamine Polymers 0.000 claims description 9
- ALQLPWJFHRMHIU-UHFFFAOYSA-N 1,4-diisocyanatobenzene Chemical compound O=C=NC1=CC=C(N=C=O)C=C1 ALQLPWJFHRMHIU-UHFFFAOYSA-N 0.000 claims description 8
- 239000005057 Hexamethylene diisocyanate Substances 0.000 claims description 8
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 claims description 8
- DVKJHBMWWAPEIU-UHFFFAOYSA-N toluene 2,4-diisocyanate Chemical compound CC1=CC=C(N=C=O)C=C1N=C=O DVKJHBMWWAPEIU-UHFFFAOYSA-N 0.000 claims description 8
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 7
- NAQMVNRVTILPCV-UHFFFAOYSA-N hexane-1,6-diamine Chemical compound NCCCCCCN NAQMVNRVTILPCV-UHFFFAOYSA-N 0.000 claims description 7
- 230000001965 increasing effect Effects 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 claims description 6
- JLDSOYXADOWAKB-UHFFFAOYSA-N aluminium nitrate Chemical compound [Al+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O JLDSOYXADOWAKB-UHFFFAOYSA-N 0.000 claims description 6
- 239000013067 intermediate product Substances 0.000 claims description 6
- CBCKQZAAMUWICA-UHFFFAOYSA-N 1,4-phenylenediamine Chemical compound NC1=CC=C(N)C=C1 CBCKQZAAMUWICA-UHFFFAOYSA-N 0.000 claims description 5
- 229920000877 Melamine resin Polymers 0.000 claims description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 5
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 5
- 230000002194 synthesizing effect Effects 0.000 claims description 5
- ROSDSFDQCJNGOL-UHFFFAOYSA-N Dimethylamine Chemical compound CNC ROSDSFDQCJNGOL-UHFFFAOYSA-N 0.000 claims description 4
- GGNQRNBDZQJCCN-UHFFFAOYSA-N benzene-1,2,4-triol Chemical compound OC1=CC=C(O)C(O)=C1 GGNQRNBDZQJCCN-UHFFFAOYSA-N 0.000 claims description 4
- VHRGRCVQAFMJIZ-UHFFFAOYSA-N cadaverine Chemical compound NCCCCCN VHRGRCVQAFMJIZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000008187 granular material Substances 0.000 claims description 4
- 239000002808 molecular sieve Substances 0.000 claims description 4
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 4
- 238000005470 impregnation Methods 0.000 claims description 3
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Inorganic materials [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 claims description 3
- ZWVMLYRJXORSEP-UHFFFAOYSA-N 1,2,6-Hexanetriol Chemical compound OCCCCC(O)CO ZWVMLYRJXORSEP-UHFFFAOYSA-N 0.000 claims description 2
- SBJCUZQNHOLYMD-UHFFFAOYSA-N 1,5-Naphthalene diisocyanate Chemical compound C1=CC=C2C(N=C=O)=CC=CC2=C1N=C=O SBJCUZQNHOLYMD-UHFFFAOYSA-N 0.000 claims description 2
- PWGJDPKCLMLPJW-UHFFFAOYSA-N 1,8-diaminooctane Chemical compound NCCCCCCCCN PWGJDPKCLMLPJW-UHFFFAOYSA-N 0.000 claims description 2
- SNLFYGIUTYKKOE-UHFFFAOYSA-N 4-n,4-n-bis(4-aminophenyl)benzene-1,4-diamine Chemical compound C1=CC(N)=CC=C1N(C=1C=CC(N)=CC=1)C1=CC=C(N)C=C1 SNLFYGIUTYKKOE-UHFFFAOYSA-N 0.000 claims description 2
- SNCJAJRILVFXAE-UHFFFAOYSA-N 9h-fluorene-2,7-diamine Chemical compound NC1=CC=C2C3=CC=C(N)C=C3CC2=C1 SNCJAJRILVFXAE-UHFFFAOYSA-N 0.000 claims description 2
- UHOVQNZJYSORNB-UHFFFAOYSA-N benzene Substances C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 2
- RPHKINMPYFJSCF-UHFFFAOYSA-N benzene-1,3,5-triamine Chemical compound NC1=CC(N)=CC(N)=C1 RPHKINMPYFJSCF-UHFFFAOYSA-N 0.000 claims description 2
- VKIRRGRTJUUZHS-UHFFFAOYSA-N cyclohexane-1,4-diamine Chemical compound NC1CCC(N)CC1 VKIRRGRTJUUZHS-UHFFFAOYSA-N 0.000 claims description 2
- YQLZOAVZWJBZSY-UHFFFAOYSA-N decane-1,10-diamine Chemical compound NCCCCCCCCCCN YQLZOAVZWJBZSY-UHFFFAOYSA-N 0.000 claims description 2
- PWSKHLMYTZNYKO-UHFFFAOYSA-N heptane-1,7-diamine Chemical compound NCCCCCCCN PWSKHLMYTZNYKO-UHFFFAOYSA-N 0.000 claims description 2
- WQGWDDDVZFFDIG-UHFFFAOYSA-N pyrogallol Chemical compound OC1=CC=CC(O)=C1O WQGWDDDVZFFDIG-UHFFFAOYSA-N 0.000 claims description 2
- -1 small-molecule compound Chemical class 0.000 claims description 2
- 229910021529 ammonia Inorganic materials 0.000 claims 1
- 150000003384 small molecules Chemical class 0.000 claims 1
- 229920000642 polymer Polymers 0.000 abstract description 4
- 238000009827 uniform distribution Methods 0.000 abstract description 2
- 238000013268 sustained release Methods 0.000 abstract 2
- 239000012730 sustained-release form Substances 0.000 abstract 2
- 235000013877 carbamide Nutrition 0.000 description 61
- 239000003337 fertilizer Substances 0.000 description 10
- 239000011248 coating agent Substances 0.000 description 8
- 238000000576 coating method Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 239000002861 polymer material Substances 0.000 description 7
- 238000001878 scanning electron micrograph Methods 0.000 description 6
- 235000015097 nutrients Nutrition 0.000 description 5
- 229920006254 polymer film Polymers 0.000 description 4
- 238000005507 spraying Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 241000196324 Embryophyta Species 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 241000209149 Zea Species 0.000 description 2
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 2
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 2
- 235000005822 corn Nutrition 0.000 description 2
- 230000001186 cumulative effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 150000003672 ureas Chemical class 0.000 description 2
- ZXHZWRZAWJVPIC-UHFFFAOYSA-N 1,2-diisocyanatonaphthalene Chemical compound C1=CC=CC2=C(N=C=O)C(N=C=O)=CC=C21 ZXHZWRZAWJVPIC-UHFFFAOYSA-N 0.000 description 1
- KXDHJXZQYSOELW-UHFFFAOYSA-M Carbamate Chemical compound NC([O-])=O KXDHJXZQYSOELW-UHFFFAOYSA-M 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000007259 addition reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- VSKFADHADUWCCL-UHFFFAOYSA-N carbamoperoxoic acid Chemical class NC(=O)OO VSKFADHADUWCCL-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000013270 controlled release Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000013265 extended release Methods 0.000 description 1
- 230000004720 fertilization Effects 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- RLJMLMKIBZAXJO-UHFFFAOYSA-N lead(II) nitrate Inorganic materials [O-][N+](=O)O[Pb]O[N+]([O-])=O RLJMLMKIBZAXJO-UHFFFAOYSA-N 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000000618 nitrogen fertilizer Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 229920005749 polyurethane resin Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05C—NITROGENOUS FERTILISERS
- C05C9/00—Fertilisers containing urea or urea compounds
- C05C9/005—Post-treatment
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
- C05G3/90—Mixtures of one or more fertilisers with additives not having a specially fertilising activity for affecting the nitrification of ammonium compounds or urea in the soil
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Soil Sciences (AREA)
- Pest Control & Pesticides (AREA)
- Polyurethanes Or Polyureas (AREA)
- Fertilizers (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
Abstract
本发明的一种制备缓释尿素的方法属于缓释尿素技术领域。首先利用二异氰酸酯与三羟基小分子化合物反应合成多羟基树脂预聚体；在80～100℃条件下，在预聚体中加入颗粒尿素和催化剂，反应4～8h，在尿素颗粒表面形成均匀分布的环碳酸酯中间产物，在反应混合体系中逐滴加入小分子多胺；反应完毕后，用滤网分离出固体颗粒，并放入恒温鼓风干燥箱烘干，最终获得表面为高分子聚氨酯包裹的缓释尿素。本发明具有成本低、缓释性能好、缓释时间可控等优点。
A method for preparing slow-release urea of the present invention belongs to the technical field of slow-release urea. Firstly, the polyhydroxy resin prepolymer is synthesized by the reaction of diisocyanate and trihydroxy small molecular compound; at 80-100 ℃, granular urea and catalyst are added to the prepolymer, and the reaction is carried out for 4-8 hours to form a uniform distribution on the surface of urea particles. After the reaction is completed, the solid particles are separated with a filter screen and put into a constant temperature blast drying oven for drying, and finally a polymer polyurethane surface is obtained. Encapsulated slow-release urea. The invention has the advantages of low cost, good sustained-release performance, controllable sustained-release time and the like.
Description
Technical Field
The invention belongs to the technical field of slow-release urea, and relates to a preparation method of novel slow-release urea.
Background
The fertilizer consumption of China approximately accounts for 1/3 of the total fertilizer amount of the world. But the utilization rate of the most widely applied nitrogen fertilizer in China is only 30-35%. The low utilization rate of the fertilizer leads to the need of multiple fertilization in one growth cycle of crops and the accumulation of the fertilizer at the rhizosphere of the plants, which not only can damage the cell structure of the root system of the plants, cause salt damage, lead to the yield reduction and even death of the crops, but also can damage the soil structure, lead to the soil degradation, the pollution of surface water and underground water, and the like. Therefore, the development of novel slow-release fertilizers has become one of the important fields.
The current slow-release urea fertilizer is mainly a coated slow-release urea fertilizer, and the membrane material is mainly a polyurethane resin series in early sulfur materials and high polymer materials. The preparation method is to spray the surface of the granular urea to form a film. Earlier efforts have been made with sulphur or sulphur-doped high-molecular polymer coated urea. For example, chinese patent document CN 101823923B (application No. 201010159451.1) developed a controlled release fertilizer special for corn. Although the film layer is not easy to damage after being wrapped and formed into a film, the problems of poor particle uniformity, uneven nutrient release and seedling burning exist. Most of the current achievements are focused on spraying and coating by utilizing a synthesized degradable high polymer material, or adding additives such as adhesive and the like into various raw materials of the high polymer material to directly spray the raw materials on the surface of urea to form a film. For example, chinese patent document CN 102964186B (application No. 201210447434.7), chinese patent document CN 103360184B (application No. 201310343720.3), and chinese patent document CN 106810363 a (application No. 201710033219.5). However, these results have problems that the coating is not uniform and the film layer is easily separated from the urea body.
In summary, the uniformity and controllability of the slow-release urea coating reported in the current patent still have certain problems, which leads to the unsatisfactory slow-release effect, thereby restricting the large-scale application of the slow-release urea coating in industry.
Disclosure of Invention
The invention mainly solves the technical problem of overcoming the defects of the traditional mainstream coating type slow-release urea spraying and coating mode, and provides a method for directly reacting, polymerizing and forming a film on the surface of granular urea by taking the granular urea as a reactant under the condition of no solvent. The slow release urea prepared by the method has the characteristic of good slow release effect because the surface polymer film is uniformly and tightly wrapped, and can be completely applied to farmlands.
The technical problem is solved by the following technical scheme:
a method for preparing slow-release urea comprises the steps of selecting diisocyanate and a trihydroxy micromolecule compound according to a molar ratio of 1: 1.5-3, reacting for 3-5 hours at the temperature of 60-80 ℃, and synthesizing a polyhydroxy resin prepolymer; increasing the reaction temperature to 80-100 ℃, adding granular urea with the diameter of 0.25-0.45 mm into the prepolymer, wherein the molar ratio of the polyhydroxy resin prepolymer to the granular urea is 1: 5-10 percent of catalyst with the mass percent of 10-15 percent of resin prepolymer is added to react for 4-8 hours, a uniformly distributed cyclic carbonate intermediate product is formed on the surface of urea particles, the temperature is raised to 120 ℃, and the catalyst is separated out by a sieve and a Buchner funnel when the temperature is hot; and (2) restoring the reaction temperature to 80-100 ℃, dropwise adding micromolecule polyamine into a reaction mixed system, wherein the molar ratio of the polyamine to the resin prepolymer is 0.5-1.2: 1. continuing the reaction until no ammonia gas is generated, and then reacting for 1 hour; after the reaction is finished, the temperature is raised to 100 ℃, and solid particles are quickly separated out by a filter screen when the solid particles are hot. And (3) putting the separated solid particles into a constant-temperature air-blast drying box, and drying for 48h at the temperature of 70 ℃ to finally obtain the slow-release urea with the surface coated by the macromolecular polyurethane.
The diisocyanate is one or two of Toluene Diisocyanate (TDI), 4 '-diphenylmethane diisocyanate (4, 4' -MDI), Hexamethylene Diisocyanate (HDI), 1, 5-Naphthalene Diisocyanate (NDI) and p-phenylene diisocyanate (PPDI).
The trihydroxy micromolecule compound is one or two of glycerol, 1,2, 4-butanetriol, 1,2, 6-hexanetriol, pyrogallic acid and 1,2, 4-benzenetriol.
The catalyst is a bimetallic supported solid base catalyst prepared by a conventional impregnation method. The alkali metal salt used is Mg (NO)3)2、Ca(NO3)2、Al(NO3)3、Zn(NO3)2、Pb(NO3)2Two kinds of (1); the carrier is one of ZMS-5, MCM-41, SBA-15, HY molecular sieve and NaY molecular sieve.
The micromolecule polyamine is one or more of p-phenylenediamine, 1, 3-propane diamine, 1, 5-pentane diamine, 1, 6-hexane diamine, 1, 7-diamino heptane, 1, 8-octane diamine, 1, 10-decane diamine, 1, 4-benzene dimethylamine, diethylene triamine, 2, 7-diamino fluorene, 1, 4-diamino cyclohexane, tri (4-aminophenyl) amine, melamine and 1,3, 5-benzene triamine.
Wherein the optimized conditions of each reactant are as follows:
the optimized diisocyanate is one or two of Toluene Diisocyanate (TDI), 4 '-diphenylmethane diisocyanate (4, 4' -MDI), Hexamethylene Diisocyanate (HDI) and p-phenylene diisocyanate (PPDI).
The optimized trihydroxy micromolecule compound is one or two of glycerol and 1,2, 4-butanetriol.
The optimized catalyst is Mg (NO)3)2、Al(NO3)3、Zn(NO3)2The two of the above-mentioned materials and one of ZMS-5, MCM-41 and HY type molecular sieve are adopted and conventional impregnation method is adopted to prepare the obtained bimetal supported solid base catalyst.
The optimized small molecular polyamine is one or more of p-phenylenediamine, 1, 3-propane diamine, 1, 6-hexane diamine, diethylene triamine and melamine.
Five-membered cyclic carbonates formed from urea and dihydroxy compounds of the present invention can undergo addition reactions with amines to form hydroxy carbamates. It is important that the carbon atom in the carbamate structural unit has a hydroxyl group generated in the reaction process, and the hydroxyl group and the carbonyl group can form an intramolecular hydrogen bond. Can reduce the sensitivity of the whole PU (namely polyurethane) material and improve the hydrolytic stability. Meanwhile, the existence of hydrogen bonds structurally makes up the weak bond structure in the traditional PU, improves the chemical resistance of the product, obviously reduces the permeability and also enhances the thermal stability. In addition, the PU material synthesized by the method has few pores, so that the PU material is easier to store and construct. Can obviously make up for the defects of the prior method.
Has the advantages that:
1. the synthesized resin prepolymer is directly used as a solvent, so that the influence and cost caused by an organic solvent are removed;
2. in the presence of a catalyst, granular urea is directly used as a raw material, cyclic carbonate intermediate synthesis is carried out on the surface of the urea, and then micromolecular polyamine is dripped for polymerization, so that the prior coating spraying process is fundamentally changed, and the problems of uneven surface spraying and incomplete coating are solved, thereby enhancing the slow release performance;
3. the amount of the surface cyclic carbonate generated can be controlled by controlling the reaction time, so that the thickness of the final slow-release urea surface polymer film is controlled, and the aim of controlling the slow-release time is fulfilled.
Drawings
FIG. 1 is an SEM image of the whole of a slow release urea prepared according to the procedure of example 1.
FIG. 2 is a scanning electron micrograph of a cross section of the urea-released composition prepared according to the procedure of example 1.
FIG. 3 is an SEM image of the whole of the slow release urea prepared according to the procedure of example 2.
FIG. 4 is a scanning electron micrograph of a cross section of a urea-released composition prepared according to the procedure of example 2.
Detailed Description
Example 1
0.06mol of 4, 4' -MDI was selected and mixed with 0.04mol of TDI, and heated and stirred at 70 ℃ for 1 h. Adding 0.2mol of glycerol, keeping the temperature unchanged, and reacting for 3 hours to synthesize the polyhydroxy resin prepolymer. The reaction temperature is increased to 90 ℃, and 0.5mol of granular urea with the diameter of 0.25-0.45 mm is added into the prepolymer. MgZnO/ZMS-5 is selected as a catalyst, 5g of the catalyst is added into the reaction system, the temperature is kept for reaction for 6 hours, and the uniformly distributed cyclic carbonate intermediate product is formed on the surface of urea particles. The temperature was raised to 120 ℃ and the catalyst was separated off while hot using a sieve and a buchner funnel. And (3) restoring the reaction temperature to 90 ℃, dropwise adding a mixture of 0.05mol of 1, 3-propanediamine and 0.05mol of 1, 6-hexanediamine into the reaction mixed system, and continuing the reaction for 1h after no ammonia gas is generated. After the reaction is finished, the temperature is raised to 100 ℃, and the prepared slow-release urea particles are quickly separated by a filter screen when the temperature is hot. And (3) putting the separated slow-release Urea particles into a constant-temperature air-blast drying oven, and drying for 48h at the temperature of 70 ℃ to obtain the slow-release Urea with the surface coated by the polymer polyurethane, which is marked as PU/Urea @ MgZnO/ZMS-5.
The obtained whole and cross-section scanning electron micrographs of the slow-release urea are respectively shown in fig. 1 and fig. 2. From FIG. 1, it can be seen that the polymer film is completely formed on the whole surface of the urea granule. Although the surface of the granular urea is not flat, the surface of the granular urea is coated with a uniform polymer material in both a protruding part and a sunken part. As can be seen from the cross-sectional view of FIG. 2, the surface of the film is clear and has a layer of uniform polymer material, and the polymer film is very tightly combined with the urea phase, and the phenomenon of phase separation does not occur, thus proving the effectiveness of the method.
Example 2
0.05mol of HDI was selected and mixed with 0.05mol of PPDI, and the mixture was heated and stirred at 75 ℃ for 1 hour. Adding 0.25mol of 1,2, 4-butanetriol, keeping the temperature unchanged, reacting for 4 hours, and synthesizing the polyhydroxy resin prepolymer. The reaction temperature is increased to 80 ℃, and 0.7mol of granular urea with the diameter of 0.25-0.45 mm is added into the prepolymer. MgAlO/HY is selected as a catalyst, 6g of the catalyst is added into a reaction system, the temperature is kept for reaction for 8 hours, and a uniformly distributed cyclic carbonate intermediate product is formed on the surface of urea particles. The temperature was raised to 120 ℃ and the catalyst was separated off while hot using a sieve and a buchner funnel. And (3) restoring the reaction temperature to 80 ℃, dropwise adding 0.03mol of diethylenetriamine and 0.04mol of melamine mixture into the reaction mixed system, and continuing the reaction for 1h after no ammonia gas is generated. After the reaction is finished, the temperature is raised to 100 ℃, and the prepared slow-release urea particles are quickly separated by a filter screen when the temperature is hot. And (3) putting the separated slow-release Urea particles into a constant-temperature air-blast drying box, and drying for 48h at the temperature of 70 ℃ to obtain the slow-release Urea with the surface coated by the macromolecular polyurethane, wherein the slow-release Urea is marked as PU/Urea @ MgAlO/HY.
The scanning electron micrographs of the whole and the cross section of the obtained slow-release urea are respectively shown in fig. 3 and fig. 4. It can be seen from the figure that the slow release urea prepared by the process of example 2 still has the outer surface completely wrapped by the polymer material, the polymer material film layer is clearly visible, and the slow release urea is very tightly combined with the urea.
Example 3
0.06mol of 4, 4' -MDI was selected and mixed with 0.04mol of TDI, and heated and stirred at 70 ℃ for 1 h. Adding 0.1mol of glycerol and 0.2mol of 1,2, 4-butanetriol, keeping the temperature unchanged, reacting for 5 hours, and synthesizing the polyhydroxy resin prepolymer. The reaction temperature is increased to 85 ℃, and 0.5mol of granular urea with the diameter of 0.25-0.45 mm is added into the prepolymer. AlZnO/MCM-41 is selected as a catalyst, 5g of the catalyst is added into a reaction system, the temperature is kept for reaction for 8 hours, and a uniformly distributed cyclic carbonate intermediate product is formed on the surface of urea particles. The temperature was raised to 120 ℃ and the catalyst was separated off while hot using a sieve and a buchner funnel. And (3) restoring the reaction temperature to 85 ℃, dropwise adding a mixture of 0.06mol of p-phenylenediamine and 0.05mol of 1, 3-propane diamine into the reaction mixed system, reacting until no ammonia gas is generated, and continuing the reaction for 1h to finish the reaction. After the reaction is finished, the temperature is raised to 100 ℃, and the prepared slow-release urea particles are quickly separated by a filter screen when the temperature is hot. And (3) putting the separated slow-release Urea particles into a constant-temperature air-blast drying box, and drying for 48h at the temperature of 70 ℃ to obtain the slow-release Urea with the surface coated by the macromolecular polyurethane, which is marked as PU/Urea @ AlZnO/MCM-41.
Example 4
0.05mol of HDI was selected and mixed with 0.05mol of PPDI, and the mixture was heated and stirred at 80 ℃ for 1 hour. Adding 0.05mol of glycerol and 0.1mol of 1,2, 4-butanetriol, keeping the temperature unchanged, reacting for 4 hours, and synthesizing the polyhydroxy resin prepolymer. The reaction temperature is increased to 100 ℃, and 1.0mol of granular urea with the diameter of 0.25-0.45 mm is added into the prepolymer. MgAlO/ZMS-5 is selected as a catalyst, 6.5g of the catalyst is added into the reaction system, the temperature is kept for reaction for 8h, and the cyclic carbonate intermediate product is formed in a uniform distribution on the surface of urea particles. The temperature was raised to 120 ℃ and the catalyst was separated off while hot using a sieve and a buchner funnel. And (3) restoring the reaction temperature to 100 ℃, dropwise adding a mixture of 0.06mol of diethylenetriamine and 0.06mol of 1, 6-hexamethylene diamine into the reaction mixed system, and continuing the reaction for 1h after the reaction is carried out until no ammonia gas is generated. After the reaction is finished, the prepared slow-release urea granules are quickly separated by using a filter screen when the granules are hot. And (3) putting the separated slow-release Urea particles into a constant-temperature air-blast drying box, and drying for 48h at the temperature of 70 ℃ to obtain the slow-release Urea with the surface coated by the polymer polyurethane, which is marked as PU/Urea @ MgAlO/ZMS-5.
Example 5
The nutrient release performance of the different slow release ureas prepared in examples 1-4 above was determined by water immersion method. The cumulative release rates of the nutrients of the four prepared slow release ureas over time are as follows.
TABLE 1 cumulative release rate of nutrients over time for extended release urea prepared in different examples
As can be seen from the data in Table 1, the slow release urea fertilizer prepared by the invention has a phase of relatively fast nutrient release within a time range of 60 to 75 days under water immersion. The time is very consistent with the time period of the big flare period of the northeast corn, the fertilizer requirement time of vegetation can be well matched, and the slow-release urea is very stable and efficient.
Claims (4)
1. A method for preparing slow-release urea comprises the steps of selecting diisocyanate and a trihydroxy micromolecule compound according to a molar ratio of 1: 1.5-3, reacting for 3-5 hours at the temperature of 60-80 ℃, and synthesizing a polyhydroxy resin prepolymer; increasing the reaction temperature to 80-100 ℃, adding granular urea with the diameter of 0.25-0.45 mm into the prepolymer, wherein the molar ratio of the polyhydroxy resin prepolymer to the granular urea is 1: 5-10, adding a catalyst which is 10-15% of the resin prepolymer by mass, reacting for 4-8 h, forming a uniformly distributed cyclic carbonate intermediate product on the surface of urea granules, increasing the temperature to 120 ℃, and separating the catalyst by using a sieve and a Buchner funnel while the temperature is hot; recovering the reaction temperature to 80-100 ℃, and dropwise adding micromolecule polyamine into a reaction mixed system, wherein the molar ratio of polyamine to resin prepolymer is 0.5-1.2: 1; continuing to react for 1h until no ammonia is generated; after the reaction is finished, raising the temperature to 100 ℃, and quickly separating solid particles by using a filter screen while the solid particles are hot; drying the separated solid particles at the temperature of 70 ℃ for 48h to finally obtain the slow-release urea with the surface coated by the macromolecular polyurethane;
the diisocyanate is one or two of toluene diisocyanate, 4' -diphenylmethane diisocyanate, hexamethylene diisocyanate, 1, 5-naphthalene diisocyanate and p-phenylene diisocyanate;
the trihydroxy micromolecule compound is one or two of glycerol, 1,2, 4-butanetriol, 1,2, 6-hexanetriol, pyrogallic acid and 1,2, 4-benzenetriol;
the catalyst is Mg (NO)3)2、Al(NO3)3、Zn(NO3)2The two of the above-mentioned materials and one of ZMS-5, MCM-41 and HY type molecular sieve are adopted to prepare the obtained bimetal supported solid base catalyst by adopting conventional impregnation method;
the micromolecule polyamine is one or more of p-phenylenediamine, 1, 3-propane diamine, 1, 5-pentane diamine, 1, 6-hexane diamine, 1, 7-diamino heptane, 1, 8-octane diamine, 1, 10-decane diamine, 1, 4-benzene dimethylamine, diethylene triamine, 2, 7-diamino fluorene, 1, 4-diamino cyclohexane, tri (4-aminophenyl) amine, melamine and 1,3, 5-benzene triamine.
2. The method for preparing slow-release urea according to claim 1, wherein the diisocyanate is one or two of toluene diisocyanate, 4' -diphenylmethane diisocyanate, hexamethylene diisocyanate and p-phenylene diisocyanate.
3. The method for preparing slow-release urea of claim 1, wherein the trihydroxy small-molecule compound is one or two of glycerol and 1,2, 4-butanetriol.
4. The method for preparing slow-release urea according to any one of claims 1-3, wherein the small-molecule polyamine is one or more of p-phenylenediamine, 1, 3-propanediamine, 1, 6-hexanediamine, diethylenetriamine and melamine.
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